Magnetic recording head with specified thickness and saturation magnetic flux density products for STO magnetic layers

ABSTRACT

According to one embodiment, a magnetic recording head includes a magnetic pole, a stacked body, and a first non-magnetic layer. The stacked body includes a first magnetic layer, a second magnetic layer provided between the first magnetic layer and the magnetic pole, and a non-magnetic intermediate layer provided between the first magnetic layer and the second magnetic layer. The first non-magnetic layer is provided between the second magnetic layer and the magnetic pole, and contacts the magnetic pole and the second magnetic layer. The first magnetic layer has a first thickness and a first saturation magnetic flux density. The second magnetic layer has a second thickness and a second saturation magnetic flux density. A second product of the second thickness and the second saturation magnetic flux density is larger than a first product of the first thickness and the first saturation magnetic flux density.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of application Ser. No. 15/841,364, filed Dec. 14,2017, which is a division of application Ser. No. 15/254,236, filed Sep.1, 2016 (now U.S. Pat. No. 9,886,971, issued Feb. 6, 2018), both ofwhich are incorporated herein by reference.

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2015-251896, filed on Dec. 24, 2015; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a magnetic recordinghead and a magnetic recording and reproducing device.

BACKGROUND

Information is recorded in a magnetic storage medium such as a HDD (HardDisk Drive), etc., using a magnetic recording head. It is desirable toincrease the recording density of the magnetic recording head and themagnetic recording and reproducing device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A to FIG. 1C are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a first embodiment;

FIG. 2A and FIG. 2B are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a first reference example;

FIG. 3A and FIG. 3B are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a second reference example;

FIG. 4A and FIG. 4B are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a third reference example;

FIG. 5A to FIG. 5D are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing device;

FIG. 6A to FIG. 6D are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing device;

FIG. 7A to FIG. 7D are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing device;

FIG. 8 is a graph of characteristics of the magnetic recording head andthe magnetic recording and reproducing device according to the firstembodiment;

FIG. 9 is a graph of characteristics of the magnetic recording head andthe magnetic recording and reproducing device according to the firstembodiment;

FIG. 10 is a graph of characteristics of the magnetic recording head andthe magnetic recording and reproducing device according to the firstembodiment;

FIG. 11A to FIG. 11C are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing deviceaccording to the first embodiment;

FIG. 12A to FIG. 12C are schematic cross-sectional views illustratinganother magnetic recording head and another magnetic recording andreproducing device according to the first embodiment;

FIG. 13A to FIG. 13C are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a second embodiment;

FIG. 14A to FIG. 14C are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a third embodiment;

FIG. 15 is a schematic perspective view illustrating a portion of amagnetic recording and reproducing device according to a fourthembodiment;

FIG. 16 is a schematic perspective view illustrating the magneticrecording and reproducing device according to the embodiment; and

FIG. 17A and FIG. 17B are schematic perspective views illustrating aportion of the magnetic recording and reproducing device.

DETAILED DESCRIPTION

According to one embodiment, a magnetic recording head includes amagnetic pole, a stacked body, and a first non-magnetic layer. Thestacked body includes a first magnetic layer, a second magnetic layerprovided between the first magnetic layer and the magnetic pole, and anon-magnetic intermediate layer provided between the first magneticlayer and the second magnetic layer. The first non-magnetic layer isprovided between the second magnetic layer and the magnetic pole, andcontacts the magnetic pole and the second magnetic layer. The firstmagnetic layer has a first thickness and a first saturation magneticflux density. The first thickness is along a first direction from thesecond magnetic layer toward the first magnetic layer. The secondmagnetic layer has a second thickness along the first direction and asecond saturation magnetic flux density. A second product of the secondthickness and the second saturation magnetic flux density is larger thana first product of the first thickness and the first saturation magneticflux density. A current flows from the second magnetic layer toward thefirst magnetic layer.

According to one embodiment, a magnetic recording head includes amagnetic pole, a shield, a stacked body, and a first non-magnetic layer.The stacked body includes a first magnetic layer provided between themagnetic pole and the shield, a second magnetic layer provided betweenthe first magnetic layer and the shield, and a non-magnetic intermediatelayer provided between the first magnetic layer and the shield. Thefirst non-magnetic layer is provided between the second magnetic layerand the shield, and contacts the shield and the second magnetic layer.The first magnetic layer has a first thickness and a first saturationmagnetic flux density. The first thickness is along a first directionfrom the second magnetic layer toward the first magnetic layer. Thesecond magnetic layer has a second thickness along the first directionand a second saturation magnetic flux density. A second product of thesecond thickness and the second saturation magnetic flux density islarger than a first product of the first thickness and the firstsaturation magnetic flux density. A current flows from the secondmagnetic layer toward the first magnetic layer.

According to one embodiment, a magnetic recording head includes amagnetic pole, a shield, and a stacked body provided between themagnetic pole and the shield. The stacked body includes a first magneticlayer, a second magnetic layer being separated from the first magneticlayer in a direction crossing a direction from the magnetic pole towardthe shield, a non-magnetic intermediate layer provided between the firstmagnetic layer and the second magnetic layer. The first magnetic layerhas a first thickness and a first saturation magnetic flux density. Thefirst thickness is along a first direction from the second magneticlayer toward the first magnetic layer. The second magnetic layer has asecond thickness along the first direction and a second saturationmagnetic flux density. A second product of the second thickness and thesecond saturation magnetic flux density is larger than a first productof the first thickness and the first saturation magnetic flux density. Acurrent flows from the second magnetic layer toward the first magneticlayer.

According to one embodiment, a magnetic recording and reproducing deviceincludes one of magnetic recording heads described above, a magneticrecording medium to which information is recorded by the magnetic pole,and a controller configured to make the current flow in the stackedbody.

Various embodiments will be described hereinafter with reference to theaccompanying drawings.

The drawings are schematic or conceptual. The relationship between thethickness and the width of each portion, and the size ratio between theportions are not necessarily identical to those in reality. Furthermore,the same portion may be shown with different dimensions or ratios indifferent figures.

In the present specification and drawings, the same elements as thosedescribed previously with reference to earlier figures are labeled withlike reference numerals, and the detailed description thereof is omittedas appropriate.

(First Embodiment)

FIG. 1A to FIG. 1C are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a first embodiment.

FIG. 1B and FIG. 1C illustrate a state (operation) of the magneticrecording head and the magnetic recording and reproducing device.

As shown in FIG. 1A, a magnetic recording and reproducing device 150according to the embodiment include a magnetic recording head 110according to the embodiment and a magnetic recording medium 80. Themagnetic recording head 110 records information to the magneticrecording medium 80.

The magnetic recording head 110 includes a magnetic pole 20, a stackedbody 10, and a first non-magnetic layer 15.

The magnetic pole 20 applies a magnetic field (recording magnetic field)to the magnetic recording medium 80. The magnetic pole 20 is, forexample, a main magnetic pole.

The stacked body 10 includes a first magnetic layer 11, a secondmagnetic layer 12, and an intermediate layer 13. The second magneticlayer 12 is provided between the first magnetic layer 11 and themagnetic pole 20. The intermediate layer 13 is provided between thefirst magnetic layer 11 and the second magnetic layer 12. Theintermediate layer 13 is non-magnetic. As described later, the stackedbody 10 generates a high frequency magnetic field. The high frequencymagnetic field is applied to the magnetic recording medium 80. Recordingof information to the magnetic recording medium by the magnetic pole 20is assisted by the high frequency magnetic field. In the magneticrecording head 110, for example, high frequency assist recording isperformed. The stacked body 10 functions as, for example, a spin torqueoscillator (STO).

The first non-magnetic layer 15 is provided between the second magneticlayer 12 and the magnetic pole 20. The first non-magnetic layer 15contacts the magnetic pole 20 and the second magnetic layer 12. Amagnetic layer is not provided between the magnetic pole 20 and thesecond magnetic layer 12. The first non-magnetic layer 15 is, forexample, a metal layer. This metal layer may include an alloy. The firstnon-magnetic layer 15 may include multiple stacked films (metal films).

In this example, a shield 20 s and a second non-magnetic layer 16 arefurther provided. The stacked body 10 is disposed between the magneticpole 20 and the shield 20 s. The first non-magnetic layer 15 is disposedbetween the magnetic pole 20 and the stacked body 10. The secondnon-magnetic layer 16 is provided between the shield 20 s and thestacked body 10. In this example, the second non-magnetic layer 16 isdisposed between the first magnetic layer 11 and the shield 20 s.

The second non-magnetic layer 16 is, for example, a metal layer. Thismetal layer may include an alloy. The second non-magnetic layer 16 mayinclude multiple stacked films (metal films).

The magnetic recording head 110 opposes the magnetic recording medium80. The magnetic recording head 110 has a medium-opposing surface 51(ABS: Air Bearing Surface). The magnetic recording medium 80 movesrelative to the medium-opposing surface 51 of the magnetic recordinghead 110. A medium movement direction 85 of the magnetic recordingmedium 80 is substantially parallel to the medium-opposing surface 51.The recording magnetic field is applied from the magnetic pole 20 toeach of different positions of the magnetic recording medium 80 inaccordance with the movement of the magnetic recording medium 80. Adirection of magnetization 84 of the magnetic recording medium 80 ischanged by the recording magnetic field.

The magnetic recording medium 80 is, for example, a perpendicularmagnetization film. A state of the magnetization 84 being upward, forexample, corresponds to one of information of “1” or “0”. A state of themagnetization 84 being downward, for example, corresponds to other oneof information of “1” or “0”.

The shield 20 s is, for example, a trailing shield. For example, oneposition of the magnetic recording medium 80 opposes the shield 20 safter opposing the magnetic pole 20.

The magnetic recording head 110 is provided with a coil 25. The coil 25generates a magnetic field from the magnetic pole 20. For example, adirection of the magnetic field (for example, recording magnetic field)generated in the magnetic pole 20 changes depending on a direction of acurrent flowing in the coil 25. The direction of the current flowing inthe coil 25 corresponds to, for example, information to be recorded.

In this example, a controller 55 is further provided. The controller 55is included in the magnetic recording and reproducing device 150. Thecontroller 55 may be attached to the magnetic recording head 110.

The controller 55 is electrically connected to the coil 25. For example,a current is supplied to the coil 25 from the controller 55. Thedirection of the current is controlled by the controller 55.

The controller 55 is, for example, electrically connected to the firstnon-magnetic layer 15 and the second non-magnetic layer 16. As describedlater, the current flows in the stacked body 10. This current is, forexample, supplied by the controller 55. The first non-magnetic layer 15and the second non-magnetic layer 16 function, for example, aselectrodes. Electrical connection between the controller 55 and thefirst non-magnetic layer 15 may be via the magnetic pole 20. Electricalconnection between the controller 55 and the second non-magnetic layer16 may be via the shield 20 s.

A direction from the magnetic recording medium 80 toward the magneticrecording head 110 is taken as a Z-direction. One directionperpendicular to the Z-direction is taken as an x-direction. A directionperpendicular to the Z-direction and the X-direction is taken as aY-direction. The Z-direction is a height direction. The X-direction isalong a down track direction. The Y-direction is along a track widthdirection.

In the magnetic recording head 110, a direction from the secondnon-magnetic layer 12 toward the first non-magnetic layer 11 is taken asa first direction D1. A direction from the first magnetic layer 11toward the second magnetic layer 12 is taken as a second direction D2.The second direction D2 is antiparallel to the first direction D1. Thefirst direction D1 and the second direction D2 are, for example, alongthe X-direction. The first direction D1, the second direction D2 and theX-direction are along a stacking direction of the stacked body 10.

The first magnetic layer 11 has a first thickness t1 along the firstdirection D1. The second magnetic layer 12 has a second thickness t2along the first direction D1. The intermediate layer 13 has a thirdthickness t3 along the first direction D1. For example, a thickness ofthe stacked body 10 depends on, for example, a sum of the firstthickness t1, the second thickness t2 and the third thickness t3.

For example, in the medium-opposing surface 51, a distance (a distancealong the first direction D1) between the magnetic pole 20 and theshield 20 s is taken as a gap length g20. Decreasing the gap length g20allows the recording density to be improved. Thinning the thickness ofthe stacked body 10 allows the gap length g20 to be decreased.

In the embodiment, the first thickness t1 of the first magnetic layer 11is set to be thin relatively. Thereby, the thickness of the stacked body10 can be thin and the gap length g20 can be decreased.

In a magnetic film, a magnetic film thickness is defined. The magneticfilm thickness is a product of the thickness t of the magnetic film anda saturation magnetic flux density Bs of the magnetic film.

In the embodiment, the magnetic film thickness of the second magneticlayer 12 is larger than the magnetic film thickness of the firstmagnetic layer 11. The first magnetic layer 11 has the first thicknesst1 along the first direction D1 and a first saturation magnetic fluxdensity Bs1. The second magnetic layer 12 has the second thickness t2along the first direction D1 and a second saturation magnetic fluxdensity Bs2. In the embodiment, a second product (t2·Bs2) of the secondthickness t2 and the second saturation magnetic flux density Bs2 islarger than a first product (t1·Bs1) of the first thickness t1 and thefirst saturation magnetic flux density Bs1.

Furthermore, in the embodiment, the current flowing in the stacked body10 is a special condition. That is, in the embodiment, the current flowsfrom the second magnetic layer 12 toward the first magnetic layer 11. Inthe following, operations according to the embodiment will be described.

FIG. 1B illustrates a first operation OP1. The first operation OP1corresponds to a first state in the magnetic recording head 110. In thefirst operation OP1, a first coil current C1 flows in the coil 25. In aregion between the magnetic pole 20 and the shield 20 s, a direction ofthe first coil current C1 is, for example, reverse (antiparallel) to theY-direction.

In the first operation OP1 (first state), a first magnetic pole magneticfield Hg1 generated from the magnetic pole 20 has a component along thefirst direction D1. At this time, a first current Jc1 flows in the firstdirection D1 in the stacked body 10. At this time, a first electron flowJe1 is flown. A direction of the first electron flow Je1 is reverse to adirection of the first current Jc1. This first current Jc1 is not lessthan a threshold current at which the stacked body 10 oscillates. Atthis time, in the stacked body 10, a high frequency magnetic field Hacis generated. The high frequency magnetic field Hac is applied to themagnetic recording medium 80. The magnetization 84 of the magneticrecording medium 80 becomes easy to reverse by the high frequencymagnetic field Hac.

In the first operation OP1, a first recording magnetic field Hr1 isgenerated from the magnetic pole 20. The first recording magnetic fieldHr1 is based on the first coil current C1. The first recording magneticfield Hr1 is applied to the magnetic recording medium 80. Themagnetization 84 of the magnetic recording medium 80 is along adirection of the first recording magnetic field Hr1. For example, themagnetization 84 is reversed. For example, the high frequency assistrecording is performed. Thereby, recording of first information (forexample, one of “1” or “0”) is performed.

FIG. 1C illustrates a second operation OP2. The second operation OP2corresponds to a second state in the magnetic recording head 110. In thesecond operation OP2, a second coil current C2 flows in the coil 25. Ina region between the magnetic pole 20 and the shield 20 s, a directionof the second coil current C2 is, for example, the Y-direction.

In the second operation OP2 (second state), a second magnetic polemagnetic field Hg2 generated from the magnetic pole 20 has a componentalong the second direction D2 (reverse, antiparallel to first directionD1). Also at this time, the first current Jc1 in the first direction D1is flown. This first current Jc1 is not less than the threshold currentat which the stacked body 10 oscillates. At this time, in the stackedbody 10, the high frequency magnetic field Hac is generated. The highfrequency magnetic field Hac is applied to the magnetic recording medium80. The magnetization 84 of the magnetic recording medium 80 becomeseasy to reverse by the high frequency magnetic field Hac.

In the second operation OP2, a second recording magnetic field Hr2 isgenerated from the magnetic pole 20. The second recording magnetic fieldHr2 is based on the second coil current C2. The second recordingmagnetic field Hr2 is applied to the magnetic recording medium 80. Themagnetization 84 of the magnetic recording medium 80 is along adirection of the second recording magnetic field Hr2. For example, themagnetization 84 is reversed. For example, the high frequency assistrecording is performed. Thereby, recording of second information (forexample, other one of “1” or “0”) is performed.

As described above, in the embodiment, the first thickness t1 of thefirst magnetic layer 11 is set to be thin. Furthermore, the current(first current Jc1) flows in the stacked body 10 from the secondmagnetic layer 12 toward the first magnetic layer 11. Thereby, it hasbeen seen that the high frequency magnetic field Hac is generated fromthe stacked body 10.

In the embodiment, the gap length g20 is small due to the thin firstmagnetic layer 11. In this configuration, the high frequency magneticfield Hac is generated from the stacked body 10 by making the currentflow in the stacked body 10 in the above direction. For example, thehigh frequency assist recording is implemented by this high frequencymagnetic field Hac. Even if the gap length g20 is small, the highfrequency assist recording is possible.

According to the embodiment, a magnetic recording head capable ofimproving the recording density and a magnetic recording and reproducingdevice can be provided by the small gap length g20 and the highfrequency magnetic field Hac.

An example of the operation of the stacked body 10 in the embodimentwill be described.

FIG. 1A corresponds to, for example, the state (initial state) where thecurrent is not supplied to the coil 25. In this state, a direction ofmagnetization 12 m of the second magnetic layer 12 is the Z-direction.The second magnetic layer 12 is, for example, an in-plane magnetizationfilm. At this time, a direction of magnetization 11 m of the firstmagnetic layer 11 is −Z-direction (reverse (antiparallel) direction toZ-direction). The first magnetic layer 11 is, for example, an in-planemagnetization film. The direction of the magnetization 11 m of the firstmagnetic layer 11 is easy to change. Thereby, the first state and thesecond state are produced.

In the first state (first operation OP1) illustrated in FIG. 1B, spin isreflected at an interface between the second magnetic layer 12 and theintermediate layer 13 by the first electron flow Je1 in the seconddirection D2. The reflected spin travels to the first magnetic layer 11.The reflection spin torque is injected from the second magnetic layer 12toward the first magnetic layer 11. The magnetization 11 m of the firstmagnetic layer 11 becomes reverse to the direction of the first magneticpole magnetic field Hg1. The spin is injected from the first magneticlayer 11 toward the second magnetic layer 12 by the first electron flowJe1 in the second direction D2. The magnetization 12 m rotates in thesecond magnetic layer 12. Thereby, the high frequency magnetic field Hacis generated.

In the second state (second operation OP1) illustrated in FIG. 1C, spinis reflected at an interface between the second magnetic layer 12 andthe intermediate layer 13 by the first electron flow Je1 in the seconddirection D2. The reflected spin travels to the first magnetic layer 11.The reflected spin torque is injected from the second magnetic layer 12toward the first magnetic layer 11. The magnetization 11 m of the firstmagnetic layer 11 becomes reverse to the direction of the secondmagnetic pole magnetic field Hg2. The spin is injected from the firstmagnetic layer 11 toward the second magnetic layer 12 by the firstelectron flow Je1 in the second direction D2. The magnetization 12 mrotates in the second magnetic layer 12. Thereby, the high frequencymagnetic field Hac is generated.

The first magnetic layer 11 functions as, for example, a spin injectionlayer. The second magnetic layer 12 functions as, for example, amagnetic field generating layer.

In the embodiment, a current is flown from the second magnetic layer 12toward the first magnetic layer 11. Thereby, it has been seen that evenif the first magnetic layer is made thin, excellent oscillationcharacteristics are obtained.

In the following, an example of the characteristics of the embodimentwill be described with reference examples.

FIG. 2A and FIG. 26 are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a first reference example.

These figures show the configuration and operation of a magneticrecording head 119 x of the first reference example.

Also in the magnetic recording head 119 x, the first magnetic layer 11,the second magnetic layer 12 and the intermediate layer 13 are provided.The configurations of these magnetic layers are the same as the magneticrecording head 110. In the recording head 119 x, a current in theoperation is different from that of the magnetic recording head 110.

As shown in FIG. 2A and FIG. 2B, in the first operation OP1 and thesecond operation OP2, a second current Jc2 flows from the first magneticlayer 11 toward the second magnetic layer 12. At this time, a secondelectron flow Jet flows from the second magnetic layer 12 toward thefirst magnetic layer 11. In the magnetic recording head 119 x, the firstmagnetic layer 11 is thin, and thus the gap length g20 can be small.However, as described later, an excellent high frequency magnetic fieldis not generated. The high frequency assist recording is difficult.

FIG. 3A and FIG. 3B are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a second reference example.

These figures show the configuration and operation of a magneticrecording head 119 y of the second reference example.

Also in the magnetic recording head 119 y, the first magnetic layer 11,the second magnetic layer 12 and the intermediate layer 13 are provided.In the magnetic recording head 119 y, the first magnetic layer 11 isthicker than that of the magnetic recording head 110. On the other hand,in the magnetic recording head 119 y, a current in the operation is thesame as that of the magnetic recording head 110.

As shown in FIG. 3A and FIG. 3B, in the first operation OP1 and thesecond operation OP2, the first current Jc1 flows from the secondmagnetic layer 12 toward the first magnetic layer 11. At this time, thefirst electron flow Je1 flows from the first magnetic layer 11 towardthe second magnetic layer 12. In the magnetic recording head 119 y, thefirst magnetic layer 11 is thick, and thus the gap length g20 is large.As described later, an excellent high frequency magnetic field is notgenerated. The high frequency assist recording is difficult.

FIG. 4A and FIG. 4B are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a third reference example.

These figures show the configuration and operation of a magneticrecording head 119 z of the third reference example.

Also in the magnetic recording head 119 z, the first magnetic layer 11,the second magnetic layer 12 and the intermediate layer 13 are provided.In the magnetic recording head 119 z, the first magnetic layer 11 isthicker than that of the magnetic recording head 110. Furthermore, inthe magnetic recording head 119 z, a current in the operation isdifferent from that of the magnetic recording head 110, and is the sameas that of the magnetic recording head 119 x.

As shown in FIG. 4A and FIG. 4B, in the first operation OP1 and thesecond operation OP2, the second current Jc2 flows from the firstmagnetic layer 11 toward the second magnetic layer 12. At this time, thesecond electron flow Jet flows from the second magnetic layer 12 towardthe first magnetic layer 11. In the magnetic recording head 119 z, thefirst magnetic layer 11 is thick, and thus the gap length g20 is large.As described later, an excellent high frequency magnetic field isgenerated. The magnetic recording head 119 z has the generalconfiguration which has been known conventionally. In the magneticrecording head 119 z, the high frequency assist recording is possible.However, the gap length g20 is large, and thus the recording densitycannot be improved sufficiently.

In the following, examples of the simulation results of thecharacteristics (characteristics of magnetic recording and reproducingdevice) of these magnetic recording heads will be described. Asimulation model is as follows.

In the magnetic recording heads 110 and 119 x, a length of the firstmagnetic layer 11 in the Z-direction is 35 nm, and a length in theY-direction is 35 nm. The thickness (first thickness t1) of the firstmagnetic layer 11 in the X-direction is 4 nm. The saturation magneticflux density Bs (first saturation magnetic flux density Bs1) of thefirst magnetic layer 11 is 1.2 T (tesla). An anisotropic magnetic fieldHk of the first magnetic layer 11 is 2 kOe (kilooersted). An exchangestiffness constant in the first magnetic layer 11 is 1.4×10⁻⁶ erg/cm(erg/centimeter). A spin polarization ratio Po in the first magneticlayer 11 is 0.48.

In the magnetic recording heads 119 y and 119 z, the thickness (firstthickness t1) of the first magnetic layer 11 in the X-direction is 11nm. In the magnetic recording heads 119 y and 119 z, a perpendicularmagnetic anisotropic magnetic field Hk of the first magnetic layer 11 is18 kOe. In the magnetic recording heads 119 y and 119 z, conditionsother than these are the same as those of the magnetic recording heads110 and 119 x.

Except the first magnetic layer 11, the configuration of the stackedbody 10 is the same in the magnetic recording heads 110, 119 x, 119 yand 119 z.

A length of the second magnetic layer 12 in the Z-direction is 35 nm,and a length in the Y-direction is 35 nm. The thickness (secondthickness t2) of the second magnetic layer 12 in the X-direction is 10nm. The saturation magnetic flux density Bs (second saturation magneticflux density Bs2) of the second magnetic layer 12 is 2.2 T (tesla). Aperpendicular magnetic anisotropic magnetic field Hk of the secondmagnetic layer 12 is −4 kOe (kilooersted). An exchange stiffnessconstant in the second magnetic layer 12 is 2×10⁻⁶ erg/cm. A spinpolarization ratio Po in the second magnetic layer 12 is 0.48.

A distance (third thickness t3 of intermediate layer 13) between thefirst magnetic layer 11 and the second magnetic layer 12 is 2 nm. In theintermediate layer 13, an exchange coupling constant is 0.

In the magnetic field applied to the stacked body 10, a ratio (Hy/Hx) ofthe Y-direction component of the magnetic field to the X-directioncomponent of the magnetic field is −10%. The magnetic field applied tothe stacked body 10 is changed in a range from 0 kOe to 20 kOe. Thismagnetic field corresponds to the gap magnetic field (first magneticpole magnetic field Hg1 and second magnetic pole magnetic field Hg2).

The following examples are simulation results about the case oftransiting from the initial state to the first state (first operationOP1). In the initial state, the current is not flown in the stacked body10. In the second magnetic layer 12, the magnetic film thickness isrelatively large, and thus the magnetization 12 m of the second magneticlayer 12 is stable. The perpendicular magnetic anisotropy of the secondmagnetic layer 12 has a positive small value or a negative value. Forthis reason, in the magnetic recording heads 110, 119 x, 119 y and 119 zin the initial state, the direction of the magnetization 12 m is+Z-direction.

In the magnetic recording heads 119 y and 119 z, the magnetic filmthickness of the first magnetic layer 11 is relatively large. Theperpendicular magnetic anisotropic magnetic field of the first magneticlayer 11 has a positive large value. For this reason, the direction ofthe magnetization 11 m of the first magnetic layer 11 is stable. In themagnetic recording heads 119 y and 119 z in the initial state, thedirection of the magnetization 11 m is the first direction D1.

In contrast, in the magnetic recording heads 110 and 119 x, the magneticfilm thickness of the first magnetic layer 11 is relatively small. Theperpendicular magnetic anisotropic magnetic field of the first magneticlayer 11 is small. For this reason; the direction of the magnetization11 m of the first magnetic layer 11 is parallel to a stacked plane ofthe stacked body 10. In the magnetic recording heads 110 and 119 z inthe initial state, the direction of the magnetization 11 m is−Z-direction. When the magnetic field along the first direction D1 isapplied to the stacked body 10 in the case where the current is notflown, the average direction of the magnetization 11 m is the firstdirection D1.

In the simulation, the direction of the magnetic field (gap magneticfield Hgap) applied to the stacked body 10 is generally the firstdirection D1.

The direction of the current flown in the stacked body 10 in the firststate (first operation OP1) differs depending on the magnetic recordinghead. In the magnetic recording heads 110 and 119 y, the first currentJc1 in the first direction D1 is flown. In the magnetic recording heads119 x and 119 z, the second current Jc2 in the second direction D2 isflown. Magnitude (absolute value) of the current is changed in thesecurrent.

The magnetic recording head 119 z is a general STO, and the direction ofthe current also corresponds to a general case. The magnetic recordinghead 119 y corresponds to the case where the direction of the current isreverse to the general case in the general STO. The magnetic recordinghead 119 x corresponds to the case where the first magnetic layer 11 isthin in the direction of the current in the general STO. The magneticrecording head 110 corresponds to the case where the first magneticlayer 11 is thin and the direction of the current is reverse to thecurrent in the general STO.

FIG. 5A to FIG. 5D are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing device.

FIG. 5A to FIG. 5D correspond to the magnetic recording heads 110, 119x, 119 y and 119 z, respectively. The horizontal axis represents theintensity (kOe) of the gap magnetic field Hgap. The vertical axisrepresents the intensity (kOe) of the high frequency magnetic field Hacgenerated in the stacked body 10. These figures show four cases of acurrent density J.

As shown in FIG. 5D, in the magnetic recording head 119 z, the highfrequency magnetic field Hac with high intensity is obtained also in thehigh current density J. In this way, in the magnetic recording head 119z (the case of general current direction in the general STO), the highfrequency magnetic field Hac is obtained.

As shown in FIG. 5C, in the magnetic recording head 119 y, the intensityof the high frequency magnetic field Hac is substantially 0 in any ofthe current density J. In this way, in the magnetic recording head 119 y(the case of reverse current direction in the general STO), the highfrequency magnetic field Hac is not obtained. For this reason, in thegeneral STO (the case of the first magnetic layer 11 being thick), thesecond current Jc2 is applied. That is, the configuration of themagnetic recording head 119 z is used.

In contrast, as shown in FIG. 5B, in the magnetic recording head 119 x,the intensity of the high frequency magnetic field Hac is low even ifthe absolute value of the current density J is large. In this way, inthe case of the first magnetic layer 11 being thin, if the currentdirection (second current Jc2) applied in the general STO is used, thehigh frequency magnetic field Hac is not substantially obtained. Forthis reason, it has been conventionally considered that the firstmagnetic layer 11 is difficult to be thin.

However, as shown in FIG. 5A, in the magnetic recording head 110according to the embodiment, in the case of the large current density J,the high frequency magnetic field Hac with high intensity is obtained.In this way, in the embodiment, the current direction (second currentJc2) in the general STO is not used but the reverse direction (firstcurrent Jc1) is used. Thereby, also in the case of the first magneticlayer 11 being thin, the excellent high frequency magnetic field Hac isobtained.

Use of the current in the direction reverse to the current directionadopted in the general STO is a unique and new idea by the inventor ofthe application. Thereby, the high frequency magnetic field Hac can begenerated based on the first magnetic layer 11. Thereby, the gap lengthg20 can be small, and the magnetic recording head capable of improvingthe recording density and the magnetic recording and reproducing devicecan be provided.

FIG. 6A to FIG. 6D are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing device.

FIG. 6A to FIG. 6D correspond to the magnetic recording heads 110, 119x, 119 y and 119 z, respectively. The horizontal axis represents theintensity (kOe) of the gap magnetic field Hgap. The vertical axisrepresents a resistance R1 in the stacked body 10. The resistance R1 isa relative value. The resistance R1 corresponds to an angle between thedirection of the magnetization 11 m of the first magnetic layer 11 andthe direction of the magnetization 12 m of the second magnetic layer 12.When the resistance R1 is high (for example, 1), the direction of themagnetization 11 m of the first magnetic layer 11 is antiparallel to thedirection of the magnetization 12 m of the second magnetic layer 12.When the resistance R1 is low (for example, 0), the direction of themagnetization 11 m of the first magnetic layer 11 is parallel to thedirection of the magnetization 12 m of the second magnetic layer 12.

As shown in FIG. 6B to FIG. 6D, in the magnetic recording heads 119 x,119 y and 119 z, the resistance R1 decreases with increasing gapmagnetic field Hgap. This corresponds to that the angle between themagnetization 11 m of the first magnetic layer 11 and the magnetization12 m of the second magnetic layer 12 becomes small with increasing gapmagnetic field Hgap. With increasing gap magnetic field Hgap, thesemagnetizations become more parallel each other.

In contrast, as shown in FIG. 6A, in the magnetic recording head 110,when the absolute value of the current density 3 is large, theresistance R1 increases with increasing gap magnetic field Hgap. Thiscorresponds to that, in the case where the current density (largecurrent on some level) having the high absolute value on some level isflown, when the gap magnetic field becomes large, the magnetization 11 mof the first magnetic layer 11 reverses from the initial state. At thecurrent density 3 like this, the high frequency magnetic field Hac withthe high intensity shown in FIG. 5A is obtained.

In the embodiment, for example, while flowing the first current Jc1 inthe stacked body 10, a third magnetic field (gap magnetic field Hgap)having the component of the first direction D1 described above isapplied. At this time, the electrical resistance (resistance R1) betweenthe first magnetic layer 11 and the second magnetic layer 12 increaseswith the intensity of the third magnetic field. That is, the electricalresistance between the first magnetic layer 11 and the second magneticlayer 12 increases with the intensity of the magnetic field having thecomponent of the first direction D1 when the current (first current Jc1)is flown in the stacked body 10.

For example, in the magnetic recording head 110 according to theembodiment, while flowing a third current having a first range in thefirst direction D1 in the stacked body 10, the third magnetic field (gapmagnetic field Hgap) having a component of the first direction D1 isapplied. The third current is a current corresponding to the currentdensity 3 in FIG. 6A. At this time, the electrical resistance(resistance R1) between the first magnetic layer 11 and the secondmagnetic layer 12 increases with the intensity of the third magneticfield. In the example shown in FIG. 6A, the range of the third currentcorresponds to a range that the absolute value of the current density 3is not less than 4×10⁸ A/cm². The first current Jc1 is set in the rangelike this. That is, the magnitude of the first current Jc1 is in thisrange. Thereby, the excellent high frequency magnetic field Hac isobtained in the first operation OP1.

FIG. 7A to FIG. 7D are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing device.

FIG. 7A to FIG. 7D correspond to the magnetic recording heads 110, 119x, 119 y and 119 z, respectively. The horizontal axis represents theintensity (kOe) of the gap magnetic field Hgap. The vertical axisrepresents the direction M1 of the magnetization 11 m of the firstmagnetic layer 11. The direction M1 being “1” corresponds to that themagnetization 11 m is in the first direction D1. The direction M1 being“−1” corresponds to that the magnetization 11 m is in the seconddirection D2.

As shown in FIG. 7C and FIG. 7D, in the magnetic recording heads 119 yand 119 z, the direction M1 of the magnetization 11 m of the firstmagnetic layer 11 is 1. In these magnetic recording heads, the directionof the magnetization 11 m does not depend on the current and the gapmagnetic field Hgap, and is the first direction D1. In these magneticrecording heads, the direction of the magnetization 11 m does notchange.

As shown in FIG. 7B, in the magnetic recording head 119 x, in the caseof the gap magnetic field gap being 0 at any current density 3, thedirection (average direction) of the magnetization 11 m is 0. When thegap magnetic field Hgap is increased, the direction M1 approaches to 1.That is, the direction M1 of the magnetization 11 m becomes along thefirst direction D1.

As shown in FIG. 7A, in the magnetic recording head 110, in the casewhere the current density J is 0 and the gap magnetic field Hgap is 0,the direction (average direction) of the magnetization 11 m is 0. Whenthe gap magnetic field Hgap is increased at the current density J being0, the direction M1 approaches to 1. That is, the direction M1 of themagnetization 11 m becomes along the first direction D1. On the otherhand, when the gap magnetic field Hgap is increased at the currentdensity J being not 0, the direction M1 approaches to −1. That is, thedirection M1 of the magnetization 11 m changes to the second directionD2. The characteristics are peculiar to the magnetic recording head 110.

In this way, in the embodiment, the magnetization 11 m of the firstmagnetic layer 11 has the peculiar characteristics. Thereby, also in thecase of the first magnetic layer 11 being thin, the excellent highfrequency magnetic field Hac is obtained.

FIG. 8 is a graph of characteristics of the magnetic recording head andthe magnetic recording and reproducing device according to the firstembodiment.

FIG. 8 shows a frequency of the high frequency magnetic field Hacgenerated in the magnetic recording head 110. The horizontal axisrepresents the intensity (kOe) of the gap magnetic field Hgap. Thevertical axis represents a frequency f1 (GHz: gigahertz) of the highfrequency magnetic field Hac.

In the embodiment, the gap magnetic field Hgap is, for example, assumedto be 7 kOe to 20 kOe. At this time, the stable high frequency magneticfield Hac is obtained. The frequency f1 of this high frequency magneticfield Hac is, for example, not less than 5 GHz and not more than 25 GHz.

In this way, also in the embodiment, even if the first magnetic layer 11is made thin, the high frequency magnetic field Hac is obtained.

For example, in the first state (first operation OP1), the magnetization11 m of the first magnetic layer 11 has a component of the seconddirection D2. In the first state, the direction of the magnetization 11m is antiparallel to the direction of the first magnetic pole magneticfield Hg1. On the other hand, in the second state (second operationOP2), the magnetization 11 m of the first magnetic layer 11 has acomponent of the first direction D1. In the second state, the directionof the magnetization 11 m is antiparallel to the direction of the secondmagnetic pole magnetic field Hg2.

In the embodiment, in the first state and the second state like this,the stacked body 10 generates the high frequency magnetic field Hac.

As already described, the first product (t1·Bs1) of the first magneticlayer 11 is smaller than the second product (t2·Bs2) of the secondmagnetic layer 12. For example, the second product is not less than 4times of the first product. For example, the second thickness t2 is notless than 2 times of the first thickness t1.

FIG. 9 is a graph of characteristics of the magnetic recording head andthe magnetic recording and reproducing device according to the firstembodiment.

FIG. 9 shows the oscillation characteristics of the magnetic recordinghead 110. The horizontal axis represents the thickness (first thicknesst1) of the first magnetic layer 11. The vertical axis represents thecurrent density J (arbitrary unit). In FIG. 9, an oscillation startcurrent density Js and a 80% current density J80% are shown. Theoscillation start current density Js is the minimum current density J atwhich the high frequency magnetic field Hac is generated in the stackedbody 10. The 80% current density J80% is a current density J at which ahigh frequency magnetic field Hac of 80% of the maximum value of thehigh frequency magnetic field Hac is generated. In the example shown inFIG. 9, the magnetic field (gap magnetic field Hgap) applied to thestacked body 10 is 10 kOe. The gap magnetic field Hgap corresponds to,for example, the first magnetic pole magnetic field Hg1 or the secondmagnetic pole magnetic field Hg2.

As shown in FIG. 9, the low oscillation start current density Js isobtained in the case where the first thickness t1 of the first magneticlayer 11 is not less than 2 nm and not more than 9 nm. In this range,the low 80% current density J80% is obtained. In the embodiment, thefirst thickness t1 of the first magnetic layer 11 is favorable to be notless than 2 nm and not more than 9 nm. The first thickness t1 of thefirst magnetic layer 11 is further favorable to be not less than 2.5 nmand not more than 7.5 nm. Furthermore, the low oscillation start currentdensity Js and further low 80% current density J80% are obtained.

FIG. 10 is a graph of characteristics of the magnetic recording head andthe magnetic recording and reproducing device according to the firstembodiment.

FIG. 10 shows the oscillation characteristics of the magnetic recordinghead 110. The horizontal axis represents a perpendicular magneticanisotropic magnetic field MA1 (kOe) of the first magnetic layer 11. Thevertical axis represents the current density J (arbitrary unit). Theperpendicular magnetic anisotropic magnetic field MA1 is perpendicularcrystal magnetic anisotropic. When the perpendicular magneticanisotropic magnetic field MA1 is negative, the magnetization in a planeperpendicular to the stacking direction becomes easy. When theperpendicular magnetic anisotropic magnetic field MA1 is positive, themagnetization in a direction parallel to the stacking direction becomeseasy. In FIG. 10, the oscillation start current density Js and the 80%current density J80% are shown. In the example shown in FIG. 10, themagnetic field (gap magnetic field Hgap) applied to the stacked body 10is 10 kOe.

As shown in FIG. 10, in the case where the perpendicular magneticanisotropic magnetic field MA1 of the first magnetic layer 11 is notless than −7 kOe and not more than 8 kOe, the low oscillation startcurrent density Js is obtained. In this range, the low 80% currentdensity J80% is obtained. In the embodiment, the perpendicular magneticanisotropic magnetic field MA1 of the first magnetic layer 11 isfavorable to be not less than −7 kOe and not more than 8 kOe. Theperpendicular magnetic anisotropic magnetic field MA1 of the firstmagnetic layer 11 is further favorable to be not less than −5 kOe andnot more than 7 kOe. Furthermore, the low oscillation start currentdensity is and further low 80% current density J80% are obtained. Forexample, the absolute value of the perpendicular magnetic anisotropicmagnetic field MA1 of the first magnetic layer 11 may be not more than 7kOe. The absolute value of the perpendicular magnetic anisotropicmagnetic field MA1 of the first magnetic layer 11 may be not more than 5kOe.

FIG. 11A to FIG. 11C are graphs of characteristics of the magneticrecording head and the magnetic recording and reproducing deviceaccording to the first embodiment.

These figures show the oscillation characteristics of the magneticrecording head 110. In FIG. 11A, the horizontal axis represents a ratioR2/1 of a magnetic damping volume of the second magnetic layer 12 to amagnetic damping volume of the first magnetic layer 11. The firstmagnetic layer 11 has a first damping constant a1. The second magneticlayer 12 has a second damping constant a2. As already described, thefirst magnetic layer 11 has the first thickness t1 and the firstsaturation magnetic flux density Bs1. The second magnetic layer 12 hasthe second thickness t2 and the second saturation magnetic flux densityBs2. The R2/1 is (a2·t2·Bs2)/(a1·t1·Bs1). The vertical axis of FIG. 11Brepresents the normalized intensity Hacn of the high frequency magneticfield Hac generated from the stacked body 10.

As shown in FIG. 11A, the high intensity Hacn is obtained at the R2/1 ofnot less than 4 and not more than 16. The R2/1 is favorable to be notless than 4 and not more than 16. The R2/1 is further favorable to benot less than 5 and not more than 14.

In the embodiment, for example, a product of the second product (t2·Bs2)and the second damping constant a2 is favorable to be not less than 4times and not more than 16 times of a product of the first product(t1·Bs1) and the first damping constant a1.

In FIG. 11B, the horizontal axis represents a ratio RtBs of the magneticfilm thickness of the second magnetic layer 12 to the magnetic filmthickness of the first magnetic layer 11. The ratio RtBs corresponds to(t2·Bs2)/(t1·Bs1). The vertical axis of FIG. 11B represents theintensity Hacn. In this example, the first damping constant a1 is 0.03,and the second damping constant a2 is 0.04.

As shown in FIG. 11B, the high intensity Hacn is obtained at the ratioRtBs of not less than 3 and not more than 11. In the embodiment, theratio RtBs is favorable to be, for example, not less than 3 and not morethan 11. Particularly, the ratio RtBs is further favorable to be, forexample, not less than 4 and not more than 10.

In FIG. 11C, the horizontal axis represents a ratio Rt of the secondthickness t2 of the second magnetic layer 12 to the first thickness t1of the first magnetic layer 11. The ratio Rt corresponds to t2/t1. Thevertical axis of FIG. 11C represents the intensity Hacn. In thisexample, the first damping constant a1 is 0.03, and the second dampingconstant a2 is 0.04. The first saturation magnetic flux density Bs1 is1.2 T, and the second saturation magnetic flux density Bs2 is 2.2 T.

As shown in FIG. 11C, the high intensity Hacn is obtained at the ratioRt of not less than 1.5 and not more than 7. In the embodiment, theratio Rt is favorable to be, for example, not less than 1.5 and not morethan 7. Particularly, the ratio Rt is favorable to be, for example, notless than 2 and not more than 6.

In the embodiment, the magnetic pole 20 includes, for example, a FeCoalloy or a FeCoNi alloy or the like.

The shield 20 s includes, for example, a FeCo alloy or a FeCoNi alloy orthe like.

At least one of the first magnetic layer 11 or the second magnetic layer12 includes, for example, at least one of a FeCo alloy, a Heusler alloy,a [Fe/Co] artificial lattice, a [FeCoNi/Ni] artificial lattice, or a[Co/Pt] artificial lattice. At least one of the first magnetic layer 11or the second magnetic layer 12 may include a stacked film including atleast two of a FeCo alloy film, a Heusler alloy film, a [Fe/Co]artificial lattice film, a [FeCoNi/Ni] artificial lattice film, or a[Co/Pt] artificial lattice film.

The intermediate layer 13 includes, for example, at least one of Cu orAg. The intermediate layer 13 may include, for example, at least one ofan alloy including Cu or an alloy including Ag. The intermediate layer13 may include, for example, a stacked film including at least two of aCu film, an Ag film, an alloy film including Cu, or an alloy filmincluding Ag.

At least one of the first non-magnetic layer 15 or the secondnon-magnetic layer 16 includes, for example, at least one of Ta, Cu, Ptor Pd. At least one of the first non-magnetic layer 15 or the secondnon-magnetic layer 16 may include an alloy including one of them. Atleast one of the first non-magnetic layer 15 or the second non-magneticlayer 16 may include a stacked film including at least two of thosefilms.

The magnetic recording medium 80 includes, for example, a CoCrPt—SiO₂granular film.

FIG. 12A to FIG. 12C are schematic cross-sectional views illustratinganother magnetic recording head and another magnetic recording andreproducing device according to the first embodiment.

FIG. 12B and FIG. 12C illustrate states (operations) of the magneticrecording head and the magnetic recording and reproducing device.

As shown in FIG. 12A, a magnetic recording and reproducing device 150 aaccording to the embodiment include a magnetic recording head 110 aaccording to the embodiment and the magnetic recording medium 80. In theembodiment, the stacking direction of the first magnetic layer 11 andthe second magnetic layer 12 is slanted to the medium-opposing surface51. Other than the above is the same as the magnetic recording had 110.

Also in the magnetic recording head 110 a and the magnetic recording andreproducing device 150 a, the second product of the second thickness t2and the second saturation magnetic flux density Bs2 is larger than thefirst product of the first thickness t1 and the first saturationmagnetic flux density Bs1. For example, the first thickness t1 isthinner than the second thickness t2.

As shown in FIG. 12B and FIG. 12C, the current (first current Jc1) flowsfrom the second magnetic layer 12 toward the first magnetic layer 11.Also in the magnetic recording head 110 a and the magnetic recording andreproducing device 150 a, a magnetic recording head capable of improvingthe recording density and a magnetic recording and reproducing devicecan be provided.

(Second Embodiment)

FIG. 13A to FIG. 13C are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a second embodiment.

FIG. 13B and FIG. 13C illustrate states (operations) of the magneticrecording head and the magnetic recording and reproducing device.

As shown in FIG. 13A, a magnetic recording and reproducing device 151according to the embodiment include a magnetic recording head 111according to the embodiment and the magnetic recording medium 80. In theembodiment, disposition of the first magnetic layer 11 and the secondmagnetic layer 12 is different from the disposition in the magneticrecording head 110. In the following description of the magneticrecording head 111, portions similar to the magnetic recording head 110are omitted appropriately.

The magnetic recording head 111 includes the magnetic pole 20, theshield 20 s, the stacked body 10, and the first non-magnetic layer 15.The shield 20 s is, for example, a trailing shield. The stacked body 10includes the first magnetic layer 11, the second magnetic layer 12 andthe intermediate layer 13. The first magnetic layer 11 is providedbetween the magnetic pole 20 and the shield 20 s. The second magneticlayer 12 is provided between the first magnetic layer 11 and the shield20 s. The intermediate layer 13 is provided between the first magneticlayer 11 and the second magnetic layer 12, and non-magnetic.

The first non-magnetic layer 15 is provided between the second magneticlayer 12 and the shield 20 s. The first non-magnetic layer 15 contactsthe shield 20 s and the second magnetic layer 12.

The second non-magnetic layer 16 is provided between the first magneticlayer 11 and the magnetic pole 20.

A direction from the second magnetic layer 12 toward the first magneticlayer 11 is taken as the first direction D1. The first direction D1 isreverse to the X-direction. A direction from the first magnetic layer 11toward the second magnetic layer 12 is taken as the second direction D2.The second direction D2 is the same as the X-direction.

Also in this example, the first magnetic layer 11 has the firstthickness t1 along the first direction D1 and the first saturationmagnetic flux density Bs1. The second magnetic layer 12 has the secondthickness t2 along the first direction D1 and the first saturationmagnetic flux density Bs2. Also in this example, the second product ofthe second thickness t2 and the second saturation magnetic flux densityBs2 is larger than the first product of the first thickness t1 and thefirst saturation magnetic flux density Bs1.

FIG. 13B corresponds to the first operation OP1 (first state). In thefirst state, the first magnetic pole magnetic field Hg1 generated fromthe magnetic pole 20 has a component along the second direction D2. Atthis time, the first current Jc1 in the first direction D1 flows in thestacked body 10. At this time, the direction of the first electron flowJe1 is reverse to the direction of the first current Jc1.

FIG. 13C corresponds to the second operation OP2 (second state). In thesecond state, the second magnetic pole magnetic field Hg2 generated fromthe magnetic pole 20 has a component along the first direction D1. Alsoat this time, the first current Jc1 in the first direction D1 flows inthe stacked body 10.

Due to the operations like this, even if the first magnetic layer 11 ismade thin, the excellent high frequency magnetic field Hac is obtained.Thereby, a magnetic recording head capable of improving the recordingdensity and a magnetic recording and reproducing device can be provided.

In the embodiment, the second product is favorable to be not less than 4times of the first product. The second thickness t2 is favorable to benot less than 2 times of the first thickness t1.

For example, the first thickness t1 is favorable to be not less than 2nm and not more than 9 nm. The perpendicular magnetic anisotropicmagnetic field MA1 of the first magnetic layer 11 is favorable to be,for example, not less than −7 kOe and not more than 8 kOe.

In the embodiment, the first magnetic layer 11 has a first dampingconstant a1. The second magnetic layer 12 has a second damping constanta2. At this time, a product of the second product and the second dampingconstant a2 is favorable to be not less than 4 times and not more than16 times of a product of the first product and the first dampingconstant a1.

In the embodiment, in the first state, the magnetization 11 m of thefirst magnetic layer 11 has a component of the second direction D2. Inthe second state, the magnetization Urn of the first magnetic layer 11has a component of the first direction D1.

In the first state and the second state, the stacked body 10 generatesthe high frequency magnetic field Hac. The frequency of the highfrequency magnetic field Hac is not less than 5 GHz and not more than 25GHz.

When while flowing the first current Jc1 in the stacked body 10, thethird magnetic field having a component of the first direction D1 isapplied, the electrical resistance between the first magnetic layer 11and the second magnetic layer 12 increases with the intensity of thethird magnetic field.

When while flowing a third current in the first direction D1 having afirst range in the stacked body 10, the third magnetic field having thecomponent of the first direction D1 is applied, the electricalresistance between the first magnetic layer 11 and the second magneticlayer 12 increases with the intensity of the third magnetic field. Themagnitude of the above first current Jc1 is in the first range likethis.

In the embodiment, the coil 25 may be provided. In the first state, afirst coil current C1 is supplied to the coil 25, and the first magneticpole magnetic field Hg1 is generated from the magnetic pole 20. In thesecond state, a second coil current C2 is supplied to the coil 25, andthe second magnetic pole magnetic field Hg2 is generated from themagnetic pole 20.

In the embodiment, the controller 55 may be further provided. In thefirst state, the controller 55 supplies the first coil current C1 to acoil 25 and supplies the first current Jc1 to the stacked body 10. Inthe second state, the controller 55 supplies the second coil current C2to the coil 25 and supplies the first current Jc1 to the stacked body10.

(Third Embodiment)

FIG. 14A to FIG. 14C are schematic cross-sectional views illustrating amagnetic recording head and a magnetic recording and reproducing deviceaccording to a third embodiment.

As shown in FIG. 14A, a magnetic recording and reproducing device 152according to the embodiment include a magnetic recording head 112according to the embodiment and the magnetic recording medium 80. In theembodiment, disposition of the first magnetic layer 11 and the secondmagnetic layer 12 is different from the disposition in the magneticrecording head 110. In the following description of the magneticrecording head 112, portions similar to the magnetic recording head 110are omitted appropriately.

The magnetic recording head 112 includes the magnetic pole 20, theshield 20 s, and the stacked body 10. The shield 20 s is, for example, atrailing shield. The stacked body 10 is provided between the magneticpole 20 and the shield 20 s. The stacked body 10 includes the firstmagnetic layer 11, the second magnetic layer 12 and the intermediatelayer 13. The first magnetic layer 11 is provided between the magneticpole 20 and the shield 20 s. The second magnetic layer 12 is separatedfrom the first magnetic layer 11 in a direction (in this example,Z-direction) crossing the direction from the magnetic pole 20 toward theshield 20 s. The intermediate layer 13 is provided between the firstmagnetic layer 11 and the second magnetic layer 12, and non-magnetic.

The magnetic pole 20 has the medium-opposing surface 51. A distancebetween the medium-opposing surface 51 and the first magnetic layer 11is longer than a distance between the medium-opposing surface 51 and thesecond magnetic layer 12. For example, the second magnetic layer 12 islocated between the first magnetic layer 11 and the magnetic recordingmedium 80.

A direction from the second magnetic layer 12 toward the first magneticlayer 11 is taken as the first direction D1. The first direction D1corresponds to the Z-direction. A direction from the first magneticlayer 11 toward the second magnetic layer 12 is taken as the seconddirection D2. The second direction D2 is reverse (antiparallel) to theZ-direction.

Also in this example, the first magnetic layer 11 has the firstthickness t1 along the first direction D1 and the first saturationmagnetic flux density Bs1. The second magnetic layer 12 has the secondthickness t2 along the first direction D1 and the second saturationmagnetic flux density Bs2. Also in this example, the second product ofthe second thickness t2 and the second saturation magnetic flux densityBs2 is larger than the first product of the first thickness t1 and thefirst saturation magnetic flux density Bs1.

In this example, a first insulating layer 17 and a second insulatinglayer 18 are further provided. The first insulating layer 17 is providedbetween the magnetic pole 20 and the stacked body 10. The secondinsulating layer 18 is provided between the shield 20 s and the stackedbody 10.

Also in this example, the current (first current Jc1) flows from thesecond magnetic layer 12 toward the first magnetic layer 11.

FIG. 14B corresponds to the first operation OP1 (first state). In thefirst state, the first magnetic pole magnetic field Hg1 generated fromthe magnetic pole 20 has a component along the direction (+X-direction)from the magnetic pole 20 toward the shield 20 s. The first current Jc1flows in the first direction D1 in the stacked body 10. At this time,the direction of the first electron flow Je1 is reverse to the directionof the first current Jc1.

FIG. 14C corresponds to the second operation OP2 (second state). In thesecond state, the second magnetic pole magnetic field Hg2 generated fromthe magnetic pole 20 has a component along the direction (−X-direction)from the shield 20 s toward the magnetic pole 20. Also at this time, thefirst current Jc1 flows in the first direction D1 in the stacked body10.

Due to the operations like this, even if the first magnetic layer 11 ismade thin, the excellent high frequency magnetic field Hac is obtained.Thereby, a magnetic recording head capable of improving the recordingdensity and a magnetic recording and reproducing device can be provided.

In the embodiment, the second product is favorable to be not less than 4times of the first product. The second thickness t2 is favorable to benot less than 2 times of the first thickness t1.

For example, the first thickness t1 is favorable to be not less than 2nm and not more than 9 nm. The perpendicular magnetic anisotropicmagnetic field MA1 of the first magnetic layer 11 is favorable to be,for example, not less than −7 kOe and not more than 8 kOe.

In the embodiment, the first magnetic layer 11 has a first dampingconstant a1. The second magnetic layer 12 has a second damping constanta2. At this time, a product of the second product and the second dampingconstant a2 is favorable to be not less than 4 times and not more than16 times of a product of the first product and the first dampingconstant a1.

In the embodiment, in the first state, the magnetization 11 m of thefirst magnetic layer 11 has a component of the direction from the shield20 s toward the magnetic pole 20, as shown in FIG. 14B. In the secondstate, the magnetization 11 m of the first magnetic layer 11 has acomponent of the direction from the magnetic pole 20 toward the shield20 s, as shown in FIG. 14C.

In the first state and the second state, the stacked body 10 generatesthe high frequency magnetic field Hac. The frequency of the highfrequency magnetic field Hac is not less than 5 GHz and not more than 25GHz.

When while flowing the first current Jc1 in the stacked body 10, thethird magnetic field having a component of the X-direction is applied,the electrical resistance between the first magnetic layer 11 and thesecond magnetic layer 12 increases with the intensity of the thirdmagnetic field.

In the embodiment, the coil 25 may be provided. In the first state, afirst coil current C1 is supplied to the coil 25, and the first magneticpole magnetic field Hg1 is generated from the magnetic pole 20. In thesecond state, a second coil current C2 is supplied to the coil 25, andthe second magnetic pole magnetic field Hg2 is generated from themagnetic pole 20.

In the embodiment, the controller 55 may be further provided. In thefirst state, the controller 55 supplies the first coil current C1 to thecoil 25 and supplies the first current Jc1 to the stacked body 10. Inthe second state, the controller 55 supplies the second coil current C2to the coil 25 and supplies the first current Jc1 to the stacked body10.

(Fourth Embodiment)

The fourth embodiment is accorded to a magnetic memory device. Themagnetic memory device according to the embodiment includes a magneticrecording head of one of the first to third embodiments and thevariations, and the magnetic recording medium 80. Information isrecorded to the magnetic recording medium 80 by the magnetic pole 20.The controller 55 may be further provided.

The controller 55 implements the first operation OP1 and the secondoperation OP2. In the first operation OP1 and the second operation OP2,the controller 55 supplies the first current Jc1 to the stacked body 10.

In the embodiment, the recording head further includes the coil 25. Inthe first operation OP1, the controller 55 supplies the first coilcurrent C1 to the coil 25 and generates the first magnetic pole magneticfield Hg1 from the magnetic pole 20. In the second operation OP2, thecontroller 55 supplies the second coil current C2 to the coil 25 andgenerates the second magnetic pole magnetic field Hg2 from the magneticpole 20.

In the following, the case where the magnetic recording head 110 is usedwill be described.

FIG. 15 is a schematic perspective view illustrating a portion of amagnetic recording and reproducing device according to the fourthembodiment.

FIG. 15 illustrates a head slider to which the magnetic recording headis mounted.

The magnetic recording head 110 is mounted to the head slider 3. Thehead slider 3 includes, for example, Al₂O₃/TiC, etc. The head slider 3moves relative to the magnetic recording medium 80 while flying over orcontacting the magnetic recording medium 80.

The head slider 3 has, for example, an air inflow side 3A and an airoutflow side 3B. The magnetic recording head 110 is disposed at the sidesurface of the air outflow side 3B of the head slider 3 or the like.Thereby, the magnetic recording head 110 that is mounted to the headslider 3 moves relative to the magnetic recording medium 80 while flyingover or contacting the magnetic recording medium 80.

FIG. 16 is a schematic perspective view illustrating the magneticrecording and reproducing device according to the embodiment.

FIG. 17A and FIG. 17B are schematic perspective views illustratingportions of the magnetic recording and reproducing device.

As shown in FIG. 16, the magnetic recording and reproducing device 150according to the embodiment is a device that uses a rotary actuator. Arecording medium disk 180 is mounted to a spindle motor 4 and is rotatedin the direction of arrow A by a motor that responds to a control signalfrom a drive device controller. The magnetic recording and reproducingdevice 150 according to the embodiment may include multiple recordingmedium disks 180. The magnetic recording and reproducing device 150 mayinclude a recording medium 181. For example, the magnetic recording andreproducing device 150 is a hybrid HDD (Hard Disk Drive). The recordingmedium 181 is, for example, a SSD (Solid State Drive). The recordingmedium 181 includes, for example, nonvolatile memory such as flashmemory, etc.

The head slider 3 that performs the recording and reproducing of theinformation stored in the recording medium disk 180 has a configurationsuch as that described above and is mounted to the tip of a suspension154 having a thin-film configuration. Here, for example, one of themagnetic recording heads according to the embodiments described above ismounted at the tip vicinity of the head slider 3.

When the recording medium disk 180 rotates, the medium-opposing surface(the ABS) of the head slider 3 is held at a prescribed fly height fromthe surface of the recording medium disk 180 by the balance between thedownward pressure due to the suspension 154 and the pressure generatedby the medium-opposing surface of the head slider 3. A so-called“contact-sliding” head slider 3 that contacts the recording medium disk180 may be used.

The suspension 154 is connected to one end of the arm 155 (e.g., theactuator arm). The arm 155 includes, for example, a bobbin unit holdinga drive coil, etc. A voice coil motor 156 which is one type of linearmotor is provided at one other end of the arm 155. The voice coil motor156 may include a drive coil that is wound onto the bobbin unit of thearm 155, and a magnetic circuit made of a permanent magnet and anopposing yoke that are disposed to oppose each other with the coilinterposed. The suspension 154 has one end and one other end; themagnetic recording head is mounted to the one end of the suspension 154;and the arm 155 is connected to the one other end of the suspension 154.

The arm 155 is held by ball bearings provided at two locations on andunder a bearing unit 157; and the arm 155 can be caused to rotate andslide unrestrictedly by the voice coil motor 156. As a result, themagnetic recording head is movable to any position of the recordingmedium disk 180.

FIG. 17A illustrates the configuration of a portion of the magneticrecording and reproducing device and is an enlarged perspective view ofa head stack assembly 160.

FIG. 17B is a perspective view illustrating a magnetic recording headassembly (head gimbal assembly (HGA)) 158 which is a portion of the headstack assembly 160.

As shown in FIG. 17A, the head stack assembly 160 includes the bearingunit 157, the head gimbal assembly 158, and a support frame 161. Thehead gimbal assembly 158 extends from the bearing unit 157. The supportframe 161 extends from the bearing unit 157 in the opposite direction ofthe HGA. The support frame 161 supports a coil 162 of the voice coilmotor.

As shown in FIG. 17B, the head gimbal assembly 158 includes the arm 155that extends from the bearing unit 157, and the suspension 154 thatextends from the arm 155.

The head slider 3 is mounted to the tip of the suspension 154. One ofthe magnetic recording heads according to the embodiments is mounted tothe head slider 3.

That is, the magnetic recording head assembly (the head gimbal assembly)158 according to the embodiment includes the magnetic recording headaccording to the embodiment, the head slider 3 to which the magneticrecording head is mounted, the suspension 154 that has the head slider 3mounted to one end of the suspension 154, and the arm 155 that isconnected to the other end of the suspension 154.

The suspension 154 includes lead wires (not shown) that are forrecording and reproducing signals, for a heater that adjusts the flyheight, for example, for a spin torque oscillator, etc. The lead wiresare electrically connected to electrodes of the magnetic recording headembedded in the head slider 3.

A signal processor 190 that performs recording and reproducing of thesignals to and from the magnetic recording medium by using the magneticrecording head also is provided. For example, the signal processor 190is provided on a portion of the magnetic recording and reproducingdevice 150 (see FIG. 16). The input/output lines of the signal processor190 are electrically coupled to the magnetic recording head by beingconnected to electrode pads of the head gimbal assembly 158.

In this way, the magnetic recording and reproducing device 150 accordingto the embodiment includes a magnetic recording medium, the magneticrecording head according to the embodiment recited above, a movable unitthat is relatively movable in a state in which the magnetic recordingmedium and the magnetic recording head are separated from each other orin contact with each other, a position controller that aligns themagnetic recording head at a prescribed recording position of themagnetic recording medium, and a signal processor that records andreproduces signals to and from the magnetic recording medium by usingthe magnetic recording head.

That is, the recording medium disk 180 is used as the magnetic recordingmedium recited above.

The movable unit recited above may include the head slider 3.

The position controller recited above may include the head gimbalassembly 158.

In this way, the magnetic recording and reproducing device 150 accordingto the embodiment includes the magnetic recording medium, the magneticrecording head assembly according to the embodiment, and the signalprocessor that records and reproduces signals to and from the magneticrecording medium by using the magnetic recording head mounted to themagnetic recording head assembly.

According to the embodiment, a magnetic recording and reproducing devicecapable of improving a recording density and a magnetic recording andreproducing device are provided.

In this specification, “perpendicular” and “parallel” include not onlystrictly perpendicular and strictly parallel but also, for example, thefluctuation due to manufacturing processes, etc.; and it is sufficientto be substantially perpendicular and substantially parallel.

Hereinabove, exemplary embodiments of the invention are described withreference to specific examples. However, the embodiments of theinvention are not limited to these specific examples. For example, oneskilled in the art may similarly practice the invention by appropriatelyselecting specific configurations of components included in magneticrecording heads such as shields, magnetic poles, side shields, includedin magnetic recording devices such as magnetic recording media, etc.,from known art. Such practice is included in the scope of the inventionto the extent that similar effects thereto are obtained.

Further, any two or more components of the specific examples may becombined within the extent of technical feasibility and are included inthe scope of the invention to the extent that the purport of theinvention is included.

Moreover, all magnetic recording devices practicable by an appropriatedesign modification by one skilled in the art based on the magneticrecording devices described above as embodiments of the invention alsoare within the scope of the invention to the extent that the spirit ofthe invention is included.

Various other variations and modifications can be conceived by thoseskilled in the art within the spirit of the invention, and it isunderstood that such variations and modifications are also encompassedwithin the scope of the invention.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention.

What is claimed is:
 1. A magnetic recording and reproducing device, comprising: a magnetic recording head; and a controller, the magnetic recording head including: a magnetic pole; a shield; and a stacked body provided between the magnetic pole and the shield, the stacked body including a first magnetic layer, a second magnetic layer being separated from the first magnetic layer in a direction crossing a direction from the magnetic pole toward the shield, an intermediate layer provided between the first magnetic layer and the second magnetic layer, the intermediate layer being non-magnetic, the first magnetic layer having a first thickness and a first saturation magnetic flux density, the first thickness being along a first direction from the second magnetic layer toward the first magnetic layer, the second magnetic layer having a second thickness along the first direction and a second saturation magnetic flux density, and a second product of the second thickness and the second saturation magnetic flux density being larger than a first product of the first thickness and the first saturation magnetic flux density, the controller is configured to flow a current in the stacked body from the second magnetic layer toward the first magnetic layer, wherein in a first state, a first magnetic pole magnetic field is generated from the magnetic pole, the first magnetic pole magnetic field having a component along the direction from the magnetic pole toward the shield, in a second state, a second magnetic pole magnetic field is generated from the magnetic pole, the second magnetic pole magnetic field having a component along a direction from the shield toward the magnetic pole, and in the first state, magnetization of the first magnetic layer has a component along the direction from the shield toward the magnetic pole.
 2. The device according to claim 1, wherein the magnetic pole has a medium-opposing surface, and a distance between the medium-opposing surface and the first magnetic layer is longer than a distance between the medium-opposing surface and the second magnetic layer.
 3. The device according to claim 1, wherein in the second state, the magnetization of the first magnetic layer has a component along the direction from the magnetic pole toward the shield.
 4. The device according to claim 1, wherein the shield is a trailing shield.
 5. The device according to claim 1, wherein the second product is not less than 4 times of the first product.
 6. The device according to claim 1, wherein the second thickness is not less than 2 times of the first thickness.
 7. The device according to claim 1, wherein the first thickness is not less than 2 nanometers and not more than 9 nanometers.
 8. The device according to claim 1, wherein a perpendicular magnetic anisotropic magnetic field of the first magnetic layer is not less than −7 kilooersted and not more than 9 kilooersted.
 9. The device according to claim 1, wherein the first magnetic layer has a first damping constant, the second magnetic layer has a second damping constant, and a product of the second product and the second damping constant is not less than 4 times and not more than 16 times of a product of the first product and the first damping constant.
 10. The device according to claim 1, wherein an electrical resistance between the first magnetic layer and the second magnetic layer increases with an intensity of a magnetic field having a component along the first direction when the current is flown in the stacked body.
 11. The device according to claim 1, wherein in the first state and the second state, the stacked body generates a high frequency magnetic field.
 12. The device according to claim 11, wherein a frequency of the high frequency magnetic field is not less than 5 gigahertz and not more than 25 gigahertz.
 13. The device according to claim 1, wherein the magnetic recording head further includes a coil, in the first state, a first coil current is supplied to the coil and the first magnetic pole magnetic field is generated from the magnetic pole, and in the second state, a second coil current is supplied to the coil and the second magnetic pole magnetic field is generated from the magnetic pole.
 14. The device according to claim 13, wherein the controller supplies the first coil current to the coil while supplying the current to the stacked body in a first operation, and the controller supplies the second coil current to the coil while supplying the current to the stacked body in a second operation, the second coil current being reversely directed to the first coil current.
 15. The device according to claim 1, further comprising: a magnetic recording medium, information being recorded to the magnetic recording medium by the magnetic pole.
 16. The device according to claim 15, wherein the magnetic recording medium is a perpendicular magnetic recording medium. 